Alcator C-Mod Run 950412 Information

Back to runs

Miniproposals
Miniproposal:077a
Date Filed: 2/2/1995
Title:ICRF Heating in L-mode Plasmas
First Author:Yuichi Takase
Session Leader:Yuichi Takase (shots 1-31)

Operators
Session leader(s):Yuichi Takase
Physics operator(s):Ian Hutchinson
Engineering operator(s):Vinny Bertolino,Frank Silva

Engineering Operator Run Comment
icrf l-mode

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:13:490PM
Author: To Be Determined
MP077A ICRF L-Mode (reversed BT, Ip)

SL: Takase
PO: Hutchinson
EO: Bertolino/Silva

Plan:
Start from 950406035 (0.8A, nel_04=1.4e20)
1. Take lower Ip data (0.6MA, 0.4MA)
2. Density scan @ 0.8MA
3. Higher Ip (> 1MA) data, if possible

It was not a very good day for RF. The whole morning was lost due to
power supply/hybrid problems. Plasma was reliable after problems were
fixed. However, RF had problems with arc protection circuits shutting
the RF off. We have managed to get each of them separately, but we
could not get both of them operating simultaneously. So we were not
able to obtain high power data that we wanted, but got some intermediate
power points. Most shots were 0.6MA. We had one 0.4MA shot at the end
of the run, but the density was unexpectedly high and RF tripped out.

Shot
01 Fiz
02 Fiz
03 Test EF2L test
04 Dud hybrid problem
05 Test
06 Test
07 Dud
08 Fiz
09 Fiz
10 Fiz
11 Pla 0.8MA, nel=1.4 (bumpy)
12 Fiz
13 Pla nel=0.9, no D-port, E-port 0.3MW, detached during RF
14 Fiz 0.6MA
15 Pla 0.6MA, nel=0.9, no D-port, E-port 0.5MW, 31-33kJ
16 Pla 0.6MA, nel=0.9, D-port 1MW, no E-port, 31-44kJ
17 Pla disrupted @ 0.8sec, no D-port, Camac error on E-port
18 Pla D-port 1.4MW, no E-port, seeing lots of injections
19 Pla no D-port, E-port 0.9MW, larger outer gap
20 Pla D-port 1.3MW, no E-port
21 Pla D-port 0.45MW, no E-port
22 Pla D-port 0.4MW (short), E-port 0.4MW
23 Pla no D-port, E-port 0.9MW
24 Pla no D-port, E-port 1.05MW
25 Pla D-port 0.75MW, no E-port
26 Pla higher dens, disrupt @ 0.72sec
27 Pla back to nel=1.0, no D-port, E-port 1.3MW
28 Pla no D-port, E-port 1.4MW
29 Pla D-port 1.15MW, no E-port
30 Pla D-port 1.2MW, no E-port
31 Pla 0.4MA, nel=1.5, disrupted @ 0.93sec, no RF


Physics Operator Summaries
Entered: Jul 7 2004 04:36:53:800PM
Author: To Be Determined

From: PHYSOP::HUTCH
Date: 12-APR-1995 17:47:09
Description: physop summary 950412

Physop Summary 950412
ICRF L-mode Confinement. SOL characterization with positive B.

SL:Takase
PO:Hutch
EO:Bertolino/Silva

Overview
_________
The morning was spent on power-supply woes. EF2L was giving twice its
nominal responsivity for the first two shots. Various other problems were
experienced during the attempt to diagnose it. Eventually it fixed itself
probably because of the tests. We also found that shot 2 from yesterday showed
the same symptoms, but none of the other shots thereafter did. The most
likely candidate for the cause of this problem is that the sense of one
of the two halves of the supply is intermittent.

Once the ps were fixed, it took a few shots to tune away the fizzles.
Shot 15 and after were good reliable current ramps, and most did not
disrupt unless the RF gassed them to death (17, 26).
RF was experiencing difficulties getting both transmitters on together.
Separately, each gave 1.2MW or more.

Most shots were at 0.6MA with no PS rail problems.
Shot 31 was a 0.4MA shot which ran onto EF1 voltage rails and died.
This shot illustrates a serious p_bolo inconsistency: twice the input
power is radiated!

Scorecard
_________

Shot,Duration(s),Ipmax(MA) Shot,Duration(s),Ipmax
1 0.000 0.029 2 0.000 0.045
3 0.000 0.003 4 0.000 0.013
5 0.000 0.003 6 0.000 0.003
7 0.000 0.014 8 0.000 0.047
9 0.000 0.050 10 0.000 0.050
11 1.014 0.877 12 0.000 0.024
13 1.600 0.828 14 0.000 0.047
15 1.594 0.642 16 1.592 0.644
17 0.809 0.639 18 1.585 0.639
19 1.586 0.642 20 1.579 0.644
21 1.571 0.639 22 1.563 0.642
23 1.566 0.639 24 1.559 0.639
25 1.540 0.636 26 0.727 0.660
27 1.547 0.639 28 1.546 0.642
29 1.542 0.639 30 1.553 0.639
31 0.928 0.484
Finished summary for 950412 Total of 31 shots.
31 shots. 19 plasmas. 7 fizzles. 5 duds.
Fizzle = gt 17 lt 50kA.

Detailed Log
____________
Start from 950406035. Delay segment1 gas puff to 1ms (2ms later).
Fill at 2.0e-5

1 Fiz Late breakdown 10ms. Nflux is ugly Br. EF2L 1821 A versus 1664 A.
OH2L=21522(21895). OH2U=22757(22370).
Found that EF2s are in the Br controller prior to breakdown.

Removed EF2s from the Br controller in segment 1.
2 Fiz No significant change. Examining the EF2 demands and hybrids, we
see that EF2L has its A voltage equal to the M-out demand. This
means that its responsivitiy is double what it should be, since
the sum of A and B should equal the M-out. It clearly has changed
since yesterday. There were some bus instrumentation changes on this
supply (or bus).

Long pause to play with PS.
3 PStest EF2L test under PLC control. Looks OK.
Further tests inside the PS shows no obvious internal problems.
Continuous test from the hybrid AFOLs.
Feedback signals seem to be there.

Full test.
4 PSdud Power supplies do ghastly bizzare things.
Control signals at the ps do not agree with the M-out signals.

Go and check contector to hybrid. One contector "not snug"
5 Hybrid test. Breakers open.
Engineering reports this was a null test because the PS were switched
off and this disables the digitization of the relevant signals.

Try again with PS on but breakers open.
6 Hybrid test. breakers open. All signals at the PS input look similar to
those out of hybrid. On shot 4 they were garbage.

Found that 950411002 had this same EF2L problem. Shots after that reverted
to the correct behaviour. We are therefore dealing with an itermittent.

Close breakers and try a shot.
7 PSdud OH switches did not close. This was because of the previous test.

8 Fiz Breakdown at 5.5ms. Bounces at 22ms.

Lower EF1s by 50A to 4750.
9 Fiz Very similar

EF1s to 4700. OH1 voltage to 0 from ~ 80V at 20ms.
10 Fiz Breakdown slightly earlier, 5ms; bounce at 19 ms.

RCUR offset in segment 1 to 0 from 1000.
EF1U demand to 4680 A.
11 Pla Big gas oscillation. Seems the gain is too large.

Lower nl04 gain to 4 from 8. Demand to 1e20.
Raise EF2/4 gain to 2 from .5.

12 Fiz Died inside at 15ms.

Oh1 V to -100 at .01s (from -75) lower the Bz ramp rate in the first
12 ms.
13 Pla Long ramp down. Big density event at .75s. Detachment.

Lower current to 0.6MA.
14 Fiz

Delay pulse gas to 4ms. Raise early RCUR deriv gain to 9.
15 Pla

Clearin to 1.3cm, ZXU to .047m
16 Pla

RXU moved out. nl04 to 1.1.
17 Pla Disrupt at .8s. Caused by radiation/detachment at RF start.

Raise fill to 2.2. Tweak RXU some more.
18 Pla Survived the RF... just!

Clearin to 1.5cm
19 Pla Still stable but 16oHz z-oscillation.

20 Pla Ip ramp getting faster. Near bounce.

Raise fill to 2.5. BR offset to .0005 from 0.
21 Pla Lower ICRF no gas influx.

Enable Argon 20 ms at 90V.
22 Pla Boring

Ic_EF4 gain drop to 1 moved back to .35s.
23 Pla 0.9 MW RF.

Ic_EF4 demand to 2.5kA
24 Pla Less oscillation on EF4. 1.05MW RF
Quite good heating, DT=.6kV electrons and ions.

Raise nl04 to 1.4.
Feather in FSP gain rise and ZXL gain drop more slowly near .5s.
25 Pla Rf=.75 MW. Density a little low.

Raise Pulse gas V to 20V to help feedback.
26 Pla Disrupts at 0.75s. The extra density plus the RF kills it.

Put nl04 demand back to 1.1 but leave the V tweak in.
27 Pla OK. Reasonable heating. 1.3MW from E-port.

28 Pla 1.4MW E-port.

29 Pla

30 Pla 1.2 Mw D-port

Ip to 0.4MA, OH1,2 voltages lowered .1 to.3s. zcur to -.007
zxl to 0. FSP gain shrunk to 4 from 8.
31 Pla Disrupts at 0.91s. Density rises uncontrollably, although NINJA was
puffing (as it had been on some previous ones) perhaps lower current
is doing it. It also looks like a shark-fin. EF1s on voltage rail,
looks like a VDE. This shot also illustrates a big discrepancy between
Prad-Bolo (>1.5MW for a long time) and the input power (~0.8MW).

Entered: Jul 7 2004 04:36:53:833PM
Author: To Be Determined
Physop Summary 950412
ICRF L-mode Confinement. SOL characterization with positive B.

SL:Takase
PO:Hutch
EO:Bertolino/Silva

Overview
_________
The morning was spent on power-supply woes. EF2L was giving twice its
nominal responsivity for the first two shots. Various other problems were
experienced during the attempt to diagnose it. Eventually it fixed itself
probably because of the tests. We also found that shot 2 from yesterday showed
the same symptoms, but none of the other shots thereafter did. The most
likely candidate for the cause of this problem is that the sense of one
of the two halves of the supply is intermittent.

Once the ps were fixed, it took a few shots to tune away the fizzles.
Shot 15 and after were good reliable current ramps, and most did not
disrupt unless the RF gassed them to death (17, 26).
RF was experiencing difficulties getting both transmitters on together.
Separately, each gave 1.2MW or more.

Most shots were at 0.6MA with no PS rail problems.
Shot 31 was a 0.4MA shot which ran onto EF1 voltage rails and died.
This shot illustrates a serious p_bolo inconsistency: twice the input
power is radiated!

Scorecard
_________

Shot,Duration(s),Ipmax(MA) Shot,Duration(s),Ipmax
1 0.000 0.029 2 0.000 0.045
3 0.000 0.003 4 0.000 0.013
5 0.000 0.003 6 0.000 0.003
7 0.000 0.014 8 0.000 0.047
9 0.000 0.050 10 0.000 0.050
11 1.014 0.877 12 0.000 0.024
13 1.600 0.828 14 0.000 0.047
15 1.594 0.642 16 1.592 0.644
17 0.809 0.639 18 1.585 0.639
19 1.586 0.642 20 1.579 0.644
21 1.571 0.639 22 1.563 0.642
23 1.566 0.639 24 1.559 0.639
25 1.540 0.636 26 0.727 0.660
27 1.547 0.639 28 1.546 0.642
29 1.542 0.639 30 1.553 0.639
31 0.928 0.484
Finished summary for 950412 Total of 31 shots.
31 shots. 19 plasmas. 7 fizzles. 5 duds.
Fizzle = gt 17 lt 50kA.

Detailed Log
____________
Start from 950406035. Delay segment1 gas puff to 1ms (2ms later).
Fill at 2.0e-5

1 Fiz Late breakdown 10ms. Nflux is ugly Br. EF2L 1821 A versus 1664 A.
OH2L=21522(21895). OH2U=22757(22370).
Found that EF2s are in the Br controller prior to breakdown.

Removed EF2s from the Br controller in segment 1.
2 Fiz No significant change. Examining the EF2 demands and hybrids, we
see that EF2L has its A voltage equal to the M-out demand. This
means that its responsivitiy is double what it should be, since
the sum of A and B should equal the M-out. It clearly has changed
since yesterday. There were some bus instrumentation changes on this
supply (or bus).

Long pause to play with PS.
3 PStest EF2L test under PLC control. Looks OK.
Further tests inside the PS shows no obvious internal problems.
Continuous test from the hybrid AFOLs.
Feedback signals seem to be there.

Full test.
4 PSdud Power supplies do ghastly bizzare things.
Control signals at the ps do not agree with the M-out signals.

Go and check contector to hybrid. One contector "not snug"
5 Hybrid test. Breakers open.
Engineering reports this was a null test because the PS were switched
off and this disables the digitization of the relevant signals.

Try again with PS on but breakers open.
6 Hybrid test. breakers open. All signals at the PS input look similar to
those out of hybrid. On shot 4 they were garbage.

Found that 950411002 had this same EF2L problem. Shots after that reverted
to the correct behaviour. We are therefore dealing with an itermittent.

Close breakers and try a shot.
7 PSdud OH switches did not close. This was because of the previous test.

8 Fiz Breakdown at 5.5ms. Bounces at 22ms.

Lower EF1s by 50A to 4750.
9 Fiz Very similar

EF1s to 4700. OH1 voltage to 0 from ~ 80V at 20ms.
10 Fiz Breakdown slightly earlier, 5ms; bounce at 19 ms.

RCUR offset in segment 1 to 0 from 1000.
EF1U demand to 4680 A.
11 Pla Big gas oscillation. Seems the gain is too large.

Lower nl04 gain to 4 from 8. Demand to 1e20.
Raise EF2/4 gain to 2 from .5.

12 Fiz Died inside at 15ms.

Oh1 V to -100 at .01s (from -75) lower the Bz ramp rate in the first
12 ms.
13 Pla Long ramp down. Big density event at .75s. Detachment.

Lower current to 0.6MA.
14 Fiz

Delay pulse gas to 4ms. Raise early RCUR deriv gain to 9.
15 Pla

Clearin to 1.3cm, ZXU to .047m
16 Pla

RXU moved out. nl04 to 1.1.
17 Pla Disrupt at .8s. Caused by radiation/detachment at RF start.

Raise fill to 2.2. Tweak RXU some more.
18 Pla Survived the RF... just!

Clearin to 1.5cm
19 Pla Still stable but 16oHz z-oscillation.

20 Pla Ip ramp getting faster. Near bounce.

Raise fill to 2.5. BR offset to .0005 from 0.
21 Pla Lower ICRF no gas influx.

Enable Argon 20 ms at 90V.
22 Pla Boring

Ic_EF4 gain drop to 1 moved back to .35s.
23 Pla 0.9 MW RF.

Ic_EF4 demand to 2.5kA
24 Pla Less oscillation on EF4. 1.05MW RF
Quite good heating, DT=.6kV electrons and ions.

Raise nl04 to 1.4.
Feather in FSP gain rise and ZXL gain drop more slowly near .5s.
25 Pla Rf=.75 MW. Density a little low.

Raise Pulse gas V to 20V to help feedback.
26 Pla Disrupts at 0.75s. The extra density plus the RF kills it.

Put nl04 demand back to 1.1 but leave the V tweak in.
27 Pla OK. Reasonable heating. 1.3MW from E-port.

28 Pla 1.4MW E-port.

29 Pla

30 Pla 1.2 Mw D-port

Ip to 0.4MA, OH1,2 voltages lowered .1 to.3s. zcur to -.007
zxl to 0. FSP gain shrunk to 4 from 8.
31 Pla Disrupts at 0.91s. Density rises uncontrollably, although NINJA was
puffing (as it had been on some previous ones) perhaps lower current
is doing it. It also looks like a shark-fin. EF1s on voltage rail,
looks like a VDE. This shot also illustrates a big discrepancy between
Prad-Bolo (>1.5MW for a long time) and the input power (~0.8MW).


Session Leader Comments
Apr 12 1995 08:37:21:330AM950412001Yuichi TakaseMP077A ICRF L-Mode (reversed BT, Ip)

Plan:
Start from 950406035 (800kA, nel_04=1.4e20)
Take lower Ip data (600kA, 400kA)
Density scan @ 800kA
Higher Ip (> 1MA) data, if possible

Shot 001:
Fizzle

Apr 12 1995 09:17:16:950AM950412002Yuichi TakaseShot 002:
Fizzle
Power supply (EF2L) problem being looked at.

Apr 12 1995 10:18:12:060AM950412003Yuichi TakaseShot 003:
EF2L test.

Apr 12 1995 11:29:11:350AM950412004Yuichi TakaseShot 004:
Dud, hybrid problem.

Apr 12 1995 11:29:34:570AM950412005Yuichi TakaseShot 005:
hybrid test

Apr 12 1995 11:29:53:230AM950412006Yuichi TakaseShot 006:
PS dud

Apr 12 1995 11:31:55:990AM950412006Yuichi TakaseShot 006:
hybrid test

Apr 12 1995 11:32:15:850AM950412007Yuichi TakaseShot 007:
PS dud

Apr 12 1995 11:32:30:360AM950412008Yuichi TakaseShot 008:
Fiz

Apr 12 1995 11:40:22:140AM950412009Yuichi TakaseShot 009:
Fiz

Apr 12 1995 12:06:05:820PM950412010Yuichi TakaseShot 010:
Fiz

Apr 12 1995 12:07:37:720PM950412011Yuichi TakaseShot 011:
Plasma (disrupted @ 1sec)
Bumpy plasma with nel_04=1.4 to 1.9e20.

Apr 12 1995 12:13:39:920PM950412012Yuichi TakaseShot 012:
Fizzle

Apr 12 1995 12:38:58:750PM950412013Yuichi TakaseShot 013:
Plasma
no D-port, E-port 0.3MW, nel=0.9, detached during RF
going to 0.6MA for next shot

Apr 12 1995 12:39:49:480PM950412014Yuichi TakaseShot 014:
Fizzle

Physics Operator Comments

Engineering Operator Comments
ShotTimeTypeStatusComment
108:33:01:850AMPlasmaOk
208:47:10:030AMPlasmaOk
310:04:29:780AMTestOk
410:39:05:970AMPlasmaBadhybrid signals incorrect
510:53:27:140AMTestOkdata system only
611:06:42:630AMTestOkdata only
711:17:11:320AMPlasmaBadoh switch faults
811:25:49:300AMPlasmaOk
911:37:01:770AMPlasmaOk
1011:47:18:270AMPlasmaOk
1111:57:46:430AMPlasmaOk
1212:11:55:400PMPlasmaOkno faults
1312:22:14:630PMPlasmaOkno faults
1412:37:16:610PMPlasmaOkno faults
1512:47:35:290PMPlasmaOkno faults
1601:01:38:570PMPlasmaOkno faults
1701:15:52:460PMPlasmaOkno faults
1801:28:47:130PMPlasmaOkno faults
1901:45:28:720PMPlasmaOkno faults
2002:01:43:370PMPlasmaOkno faults
2102:18:05:900PMPlasmaOkno faults
2202:34:25:480PMPlasmaOkno faults
2302:49:53:680PMPlasmaOkno faults
2403:09:52:940PMPlasmaOknofaults
2503:26:50:320PMPlasmaOkno faults
2603:45:23:940PMPlasmaOkno faults
2703:57:20:260PMPlasmaOkno faults
2804:10:21:690PMPlasmaOkno faults
2904:26:49:670PMPlasmaOk no faults
3004:39:35:950PMPlasmaOkno faults
3104:53:51:730PMPlasmaOkno faults